In the present study, we demonstrated that, in thyroid tumors, FUCA-1 expression, as analyzed by immunohistochemistry, is related with the degree of differentiation of thyroid cancers: the levels in differentiated papillary thyroid cancers examined (PTCs), were relatively high, close to those of normal thyroid tissues. The gene discussed is FUCA1; the disease is thyroid gland papillary carcinoma.